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For those contemplating a 308 stroker
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HK1837 Offline
#1 Posted : Saturday, 16 June 2007 7:19:01 PM(UTC)
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Guys

About 6 years ago I bought a VL 5L block that had been machined for rod clearance. Not knowing it had been an offset ground stroker I hot tanked it, bored and honed, new welsh plugs, new cam bearings etc etc and put a crank in on new bearings. Then when the pistons and rods were going in I discovered the pistons sticking out the deck by about 12 thou. The damn block had been decked about 60-70 thou. The block has since sat there unused as I thought it would never be any use except for an offset ground stroker. Been doing some homework, and if any of you ever come across the same thing this is what you can do.
You can buy an RPM 3.5" stroke crank to suit the 308, with Holden rod journals. If you use this crank with 308 rods and Chev 1.425" pin height dish top pistons the pistons will end up about 15 thou down the bore (these pistons are sometimes referred to as 383 stroker pistons). These cranks are cheap - too cheap in fact ($325). I have heard of problems adding mallory metal to them during balancing. But I might give it a go "just for fun" and see how it goes. The pistons are also cheap as chips in hyper-eutectic form at about $225. I am a little tentative about the quality of the crank, but the extra 20 thou stroke does push the pistons that little further up the bores of what was once a junk block, plus it is only destined for a 4000rpm 250hp tow engine. I do know people running these cranks with no troubles as well.
Does anyone have a formula for how much to take off a valley cover given how much a block has been decked?

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Sandman Offline
#2 Posted : Sunday, 17 June 2007 3:08:46 AM(UTC)
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Is the crank you have an offset grind with the rods to suit?
What stroke is it?
How did you come up with the figure of .060 - ,070"off the deck? Did you measure from the mains tunnel to the deck?
Have you bought any of the new crank yet? I may have a
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ozchevy Offline
#3 Posted : Sunday, 17 June 2007 3:47:10 AM(UTC)
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The formular is .0123 off the intake for every .010 off the surface of the block.
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HK1837 Offline
#4 Posted : Sunday, 17 June 2007 9:01:38 PM(UTC)
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The VL block didn't come with a crank. The rpm crank i'm looking at is a new crank made to suit a 308 with Holden rod and mains jornals but it is a 3.5" stroke not 3.48".
I estimated how much it had been decked by measuring a stock 308 from piston top to
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Sandman Offline
#5 Posted : Monday, 18 June 2007 2:03:12 AM(UTC)
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OK Byron, I misunderstood your original message. When you said you had fitted a crank etc, I thought you were using the offset ground one.
But regardless, if what you were using is putting the pistons .012" out of the bore, I was going to suggest gettin
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HK1837 Offline
#6 Posted : Monday, 18 June 2007 5:02:24 AM(UTC)
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Good advice Sandman. But I actually have no use for the VL block as a 308. The reason I was contemplating using it was the fact it was prepped ready to go, including rod clearances ie bored, honed, painted, cam bearings etc. The fact it has been decked me
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boom Offline
#7 Posted : Sunday, 8 July 2007 8:47:33 AM(UTC)
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quote:
Originally posted by Byron Rich

I do know people running these cranks with no troubles as well...
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HK1837 Offline
#8 Posted : Sunday, 8 July 2007 8:24:00 PM(UTC)
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I know none in and working, but have heard of them. The only reason i'm even contemplating is the block I have is basically useless unless I use one of the RPM cranks, and it's all machined, painted, new rod bearings, welsh plugs etc ready to go plus I on
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boom Offline
#9 Posted : Sunday, 8 July 2007 9:25:55 PM(UTC)
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aren't hypereutectic pistons lighter than cast? the seem alot cheaper too from the ebay place that sells the cranks ($250 or so) they're a good brand too being from hypatec. would these need balancing?

Cheers
Alex

If it doesn’t
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HK1837 Offline
#10 Posted : Monday, 9 July 2007 5:51:58 AM(UTC)
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Best ask a machine shop. I don't know. You should always balance though, particularly with a stroker.

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ozchevy Offline
#11 Posted : Tuesday, 10 July 2007 2:34:34 PM(UTC)
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Does anyone have a formula for how much to take off a valley cover given how much a block has been decked?

Maybe you missed my post previously?

Posted - 16/06/2007 : 5:47:10 PM
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HK1837 Offline
#12 Posted : Tuesday, 10 July 2007 4:05:54 PM(UTC)
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Thanks OzChevy.

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If we all had the same (good) taste, who would buy all the Fords?
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If we all had the same (good) taste, who would buy all the Fords?
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